Thermal Comfort Characteristics of Pregnant Women at Different Gestational Stages in Hospitals: A field Investigation in Cold Zone of China

Optimal thermal comfort for pregnant women in hospital environments is crucial due to their unique physiological conditions, yet research addressing their specific needs, especially changes in metabolism across pregnancy stages, is still limited. This study examined the thermal comfort of pregnant women and their accompanying individuals in hospital outpatient waiting areas over a full year in a cold zone of China, encompassing both heating and cooling seasons. A total of 2,068 questionnaires were collected, combining subjective thermal sensations with objective environmental measurements. Findings revealed that basal metabolic rate (BMR) adjusted PMV models improved prediction accuracy for pregnant women, with a 6.60% improvement observed in late pregnancy. Neutral temperatures declined with pregnancy progression, from 23.3°C to 21.6°C in the cooling season and 21.0°C to 20.3°C in the heating season, indicating increased heat sensitivity in later stages. Preferred temperatures remained relatively stable (21.1-21.8°C), while thermal sensitivity increased with pregnancy progression (Probit slopes from 0.39 to 0.61). Furthermore, adaptive PMV models (aPMV and ePMV) outperformed the standard PMV across all studied groups. The overlap of thermal comfort zones indicated seasonally adaptive temperature ranges: 20.4-24.6 °C during the cooling season, 17.6-24.8 °C in the heating season, and 17.7-24.0 °C throughout the year. Participants also preferred a relative humidity range of 40% to 65% and gentle airflow to enhance their perception of freshness. These insights offer valuable guidance for occupant-centered design and ventilation strategies in healthcare settings and contribute to the refinement of thermal comfort standards.